Non-sorted genetic algorithm optimization of cost-efficient synthetic mooring systems utilizing polymer springs for 15 mw floating wind turbines in relatively shallow waters

Abstract

The imperative transition to renewable energy sources, driven by the need to address energy security and climate change challenges, underscores the pivotal role of offshore wind energy. This study delves into the multifaceted aspects of wind energy, examining both the potential in shallow water installations and the ongoing paradigm shift towards larger turbine sizes. In exploring shallow water regions, economically viable locations for wind farms emerge between fifty and seventy meters in depth, employing shared anchor concepts and mooring line systems. The selection of an optimal system type is critical, and past research highlights the efficiency of synthetic fiber ropes over traditional chain catenary configurations. This work presents dynamic analyses of a fifteen MW turbine and the VolturnUS-S reference platform in the Celtic Sea. A comprehensive comparative assessment of planar displacements, rotations, and loads on a shared anchor is conducted using nylon and polyester ropes. Results show a notable thirty-six percent reduction in peak resolved anchor load with nylon compared to polyester, albeit with larger rotations, suggesting potential improvements in mooring design. With nylon being ten percent more cost-effective than polyester and ongoing investigations into efficient shared anchor concepts, this study encourages further exploration of nylon applications in shallow-water wind farms. Simultaneously, the wind energy sector grapples with the challenge of escalating turbine sizes to reduce the levelized cost of energy. This necessitates smaller platform and mooring systems, especially in the context of shallow-water installations. Building upon prior research, which employed a multi-objective optimization (MO) framework for designing platforms and mooring systems with synthetic lines, this study extends the existing framework by incorporating computational efficiency strategies. Utilizing a running metric as a termination criterion for the MO contributes to computational efficiency. Most importantly, at the core of this academic inquiry lies the scrutiny of cost optimization within an alternative mooring system integrating spring polymer—an unexplored domain in extant literature. The thorough analysis reveals that implementing the optimization framework yields reasonable outcomes; furthermore, its application elucidates how the alternative system can effectively mitigate costs, particularly notable for smaller radii.